Ventilation apparatuses like air conditioner or air clean machine usually are disposed with filters. Air is sucked into an internal space via an air entry and filtered with a filter before the air is sent outside via an air exit to achieve air circulation.
Usually, the filter becomes more and more dirty during usage because dirt and particles in the air are filtered and stay on the filter. Too much dirt of filters affects efficiency of circulation of ventilation apparatuses and further causes energy waste due to low efficiency. Therefore a user needs to replace filters of ventilation apparatus regularly.
Although manufacturers of ventilation apparatuses remind users with product specifications to regularly clean or replace filters, most users, however, forget to do such work, causing efficiency of ventilation apparatuses getting worse and worse while energy loss getting higher and higher.
Accordingly, current ventilation apparatuses usually are disposed with a timer to accumulate usage time of filters, i.e. operation time of ventilation apparatuses, and remind users with messages to clean or replace filters.
However, dirty levels of filters are greatly related to air condition. For example, when dirt amount is large in the air, the filters may be blocked in short time. But, in convention art, before the usage time reaches a predetermined value, such ventilation apparatus does not issue reminder messages and users are not aware of the need to replace filters. As such, before the usage time reaches the predetermined value, efficiency of such ventilation apparatus may drop significantly.
On the other hand, when dirt in the air is few, a filter may be still clean even reaching predetermined usage time. A reminder message of a ventilation apparatus in such case causes unnecessary waste.